High speed tunable matching network for antenna systems

Abstract

A communication system is provided, including an antenna, a matching network coupled to the antenna, a controller configured to host an algorithm for controlling the matching network, and a look-up table coupled to the controller. The look-up table includes characterization data according to frequency bands and conditions. The controller is configured to refer to the look-up table to determine optimum impedance for a frequency band selected under a condition detected during a time interval, and adjust the matching network to provide the optimum impedance. Part or all of the sections related to the tunable matching scheme can be integrated on a chip.

What is claimed is: 
     
       1. A communication system comprising:
 an antenna; 
 a matching network coupled to the antenna; 
 a controller configured to control the matching network; and 
 a look-up table coupled to the controller, the look-up table including characterization data according to frequency bands and conditions, 
 wherein 
 the controller is configured to refer to the look-up table to determine optimum impedance for a frequency band selected and under a condition detected during a time interval, and adjust the matching network to provide the optimum impedance, 
 and wherein 
 the controller and the look-up table are integrated on a chip; 
 further characterized in that: 
 the matching network comprises a plurality of switches, each switch coupled to one or more cells, 
 wherein 
 each cell comprises one or more capacitors, one or more inductors, or a combination of one or more capacitors and one or more inductors, 
 and wherein 
 the controller is configured to adjust the matching network by turning on one or more of the plurality of switches to provide the optimum impedance for the frequency band and the condition, based on a configuration of the cells coupled to the one or more of the plurality of switches that are turned on. 
 
     
     
       2. The communication system of  claim 1 , wherein the controller and the look-up table are integrated on a field-programmable gate array (FPGA). 
     
     
       3. The communication system of  claim 1 , wherein the matching network is integrated with the controller and the look-up table on the chip. 
     
     
       4. The communication system of  claim 3 , wherein the look-up table is implemented on a memory. 
     
     
       5. The communication system of  claim 4 , wherein the memory is a read only memory (ROM) or a random access memory (RAM). 
     
     
       6. A method for impedance matching of a communication system that includes an antenna, a matching network coupled to the antenna, a controller configured to control the matching network, and a look-up table coupled to the controller, the look-up table including characterization data according to frequency bands and conditions, wherein the controller is configured to refer to the look-up table to determine optimum impedance for a frequency band selected and under a condition detected during a time interval, and adjust the matching network to provide the optimum impedance, the method comprising:
 first adjusting the matching network to provide a first impedance that is optimum for a first frequency band and a first condition; 
 second adjusting the matching network to provide a second impedance that is optimum for a second frequency band and a second condition, wherein a transition from the first impedance to the second impedance is configured to avoid path discontinuity; and 
 third adjusting the matching network, between the first and second adjusting, to provide a third impedance based on a configuration sequence to avoid the path discontinuity during the transition from the first to the third impedance and from the third to the second impedance; 
 further characterized in that: 
 the matching network includes a plurality of switches, each switch coupled to one or more cells, wherein 
 the first adjusting comprises turning on first one or more of the plurality of switches to provide the first impedance determined b the cells coupled led to the first one or more of the plurality of switches, 
 the third adjusting comprises keeping on at least one switch of the first one or more of the plurality of switches while turning off the other switches and turning on second one or more switches coupled to the cells corresponding to the second impedance; and 
 the second adjusting comprises turning off the at least one switch of the first one or more of the plurality of switches while keeping on the second one or more switches to provide the second impedance. 
 
     
     
       7. The method of  claim 6 , wherein
 a fast switching speed is provided by integrating the controller, the look-up table and the matching network on a chip.